Generally, however, since a great number of packet directional paths are to be set for each optical fiber between adjoining nodes in a high speed packet communication network, the identification numbers for the packet directional paths are extremely variable. Therefore, a great amount of data is necessary for transfer of such a packet directional path identifier. As a result, technical advance producing more effective and efficient transfer of the packet directional path identifier have been anxiously awaited.
For example, identifiers (identification numbers) ranging from 0 to 4095 can be set for 4096 packet directional paths for each link. Conventionally, identifiers are transferred "as is" from a node to an adjoining node, for example, when transferring information on packet directional paths to be newly set between nodes; information on a packet directional path in which a fault is detected at a node (information indicating a packet directional path in which the fault has occurred); or information on a faulty packet directional path detected at an interface unit in a node, to a controller in the same node, or the like. Thus, the amount of data required for transfer of each packet directional path identifier is as much as 12 bits. Consequently 12.times.4096 bits are required in total. More specifically in the conventional packet directional path identifier transfer system, the amount of transferred information is extremely large.